Taher Saifuddin (4 August 1888 – 12 November 1965), also known as Tahir Sayf al-Din, was the 51st and longest serving Da'i al-Mutlaq of the Dawoodi Bohras. Saifuddin adapted the modernisation in Western and European ideas, and established its benefits for the Bohras, whilst still steeped in the traditions and the culture of the community's Fatimid heritage. Saifuddin laid substantial groundwork in terms of philanthropy, education, entrepreneurship, social outreach, political outreach, and community upliftment upon which his successors, Mohammed Burhanuddin and Mufaddal Saifuddin, continued to build, resulting in unprecedented era of prosperity among the Dawoodi Bohras.